The set of flip up AR-15 Front and Rear Back Up Sights for sale are low profile BUIS flip up sights made from hard anodized aircraft grade aluminum with steel hardware for year of use. This set of AR-15 flip up sights automatically locks into position when raised for fast tactical targeting. These backup iron sights for your AR-15 rifle have a posi-lock design to guarantee zero every time through the A2 front sight post. Quick detachable with adjustable front A2 square post and dual aperture for long and short range targets rear sight. 0.65 MOA on M-4 type rifles 0.49 MOA on A-4 type rifles. Sights use Same plane as hand guard rail with matching upper receiver height. Fits all AR-15, M4 and M16 flat top rifles with picatinny rail. Limited lifetime warranty.